1. Field of the Invention
The present invention relates generally to IPv6 over IEEE 802.16 networks. In particular, the present invention relates to a fast handover method for IPv6 over IEEE 802.16 networks.
2. Description of the Related Art
The recent generalization of the use of mobile stations such as a notebook computer and a Personal Digital Assistant (PDA) increases the need for high-speed wireless Internet service, and with the integration of wireless networks and the Internet, users expect the network environment in which they can freely use the Internet anytime anyplace. Accordingly, a Wireless Broadband Internet (WiBro) standard, which is a wireless Internet standard in which high-speed Internet access is possible not only in the stationary state but also in the moving state, has recently been established by Korean Telecommunications Technology Association (TTA). The WiBro standard supports mobility of 60 Km/h or below, overcoming the limitation of the existing wired system, and is so designed as to seamlessly provide high-speed wireless Internet service indoors and/or outdoors.
A mobility support method currently available in the WiBro standard is described as a Medium Access Control (MAC) protocol performed between a mobile station (MS) and a Radio Access Station (RAS) when the MS moves between RASs. However, if an MS moves to a new Access Control Router (ACR) of another subnet, it should accept an IP Mobility Support Protocol to maintain the current session in communication. Mobile Internet Protocol version 6 (MIPv6) technology established by MIP6 Working Group of Internet Engineering Task Force (IETF) is a typical international standard protocol for the IP Mobility Support. In particular, if the improved future WiBro service environment accepts IPv6 which is the next generation Internet protocol, the MIPv6 will gain in importance as Mobility Support Protocol.
The MIPv6 technology supports mobility by binding a Home Address (HoA) of an MS with a new Care-or-Address (CoA) generated by a network to which the MS moved, for a Home Agent (HA), using the dual addressing system. In particular, the MIPv6 technology can support an optimized routing path for data packets by sending the binding message even to a Correspondent Node (CN). However, MIPv6, which is a protocol simply related to location registration of an MS and route reestablishment for data packets of the current session in communication, has several problems in supporting the mobility enough to satisfy real-time communication, like Voice over IP (VoIP).
MIPv6 Signaling and Handoff Optimization (MIPSHOP) Working Group of IETF has established a Fast Mobile IPv6 (FMIPv6) protocol to make up for the defects of MIPv6 and support fast IPv6 handover. FMIPv6 is a protocol designed such that it supports a MAC Layer and detects the position to which an MS will newly move and previously exchanges information necessary for IPv6 handover and service resumption, thereby enabling fast service resumption when the movement actually occurs. FMIPv6 needs a definite mechanism for supporting events from the MAC layer and exchanging such events because it predicts mobility of an MS basically depending on the MAC layer. In addition, because the information available in the link layer differs according to link type and the timing at which the information is provided is also dependent on a protocol of the link layer, when FMIPv6 is applied to the actual network, the FMIPv6 should be redesigned such that interaction with the link layer is optimized, taking a characteristic of the corresponding link into account.